This invention relates generally to post-cataract patient care and vision improvement and, more particularly, to an intra-ocular bifocal lens implantable in a human eye to replace the natural lens, having been removed, for instance, in a cataract operation. Commonly, thick glasses have been used for correcting the vision of post-cataract patients. However, the glasses have obvious disadvantages associated with the size and weight of the glasses. The present invention circumvents the need for heavy glasses by creating a pseudophakia or an eye in which a plastic lenticulus is substituted for the extracted cataract.
The concept of creating a concentric bifocal lens has been shown for contact lenses. U.S. Pat. No. 3,726,587 is an example. Contact lenses have a converging meniscus shape in order to conform to the rounded shape of the cornea. Such a shape could not apply in an intra-ocular implantation. Other types of multiple focus contact lenses are well known. U.S. Pat. No. 3,794,414 shows a lens having a light-transmitting area interrupted by spaced-apart, opaque portions. U.S. Pat. No. 3,962,505 shows a nearly concentric portion of a contact lens for bifocal vision.
Most of the prior art related to intra-ocular lenses deals with fixation means for securing the lens in either the posterior or anterior chamber of the eye. U.S. Pat. No. 4,010,496 shows an intra-ocular lens having upper and lower refractive segments for near and far vision.